Genetic susceptibility and gastric cancer risk

Gastric cancer occurrence in preneoplastic lesions: a long-term follow-up in a high-risk area in Spain

There are no established criteria to classify patients into high or low risk of progressing to gastric cancer (GC). The aim of the study was to identify predictors of GC occurrence among patients with gastric preneoplastic lesions. A prospective and retrospective follow-up study was carried out in a province in Spain with one of the highest risk of GC. The study included 478 patients who underwent gastric biopsy in 1988-1994 with diagnoses of normal mucosa, nonatrophic gastritis (NAG), non-metaplastic multifocal atrophic gastritis (MAG) and complete or incomplete intestinal metaplasia (IM) and who accepted to undergo a new biopsy during 2005-2007 or had an event during follow up. Inter- and intra-observer variability of histological diagnosis was assessed. Analysis was done using Cox proportional hazards risk (HR) models. The mean age of the patients was 50 years, 47% were males and the mean follow-up time was 12.8 years. During follow-up, 23 GC (4.8%) were diagnosed (21 adenocarcinomas and 2 lymphomas) with an incidence of 3.77 per 1,000 person per year. The incidence rate of GC for those with incomplete IM was 16.5 per 1,000 person years. Out the 21 adenocarcinomas, 16 had an incomplete IM in the baseline diagnosis. Incomplete IM (HR 11.3; 95% CI 3.8-33.9) and a family history of GC (HR 6.1; 95% CI 1.7-22.4) were the strongest risk factors for gastric adenocarcinoma. Subtyping of IM and family history of GC may be useful for the identification of high-risk patients who need more intensive surveillance.

Roles of inflammatory cytokines in the progression of gastric cancer: friends or foes?

Increasing evidence is being reported regarding the hypothesis that several proinflammatory and anti-inflammatory cytokines may promote tumor progression and affect the host antitumor response. However, the manner in which a local cytokine network operates in tumor development remains unclear. We reviewed the literature to examine the consequences of novel insights into inflammatory cytokines associated with gastric cancer progression. The Medline and EMBASE databases were searched for publications regarding the role of inflammatory cytokines in the development of gastric cancer. A number of studies have suggested that several proinflammatory and anti-inflammatory cytokines promote tumor progression through the direct activation of nuclear factor-κB (NF-κB) and the upregulation of angiogenesis and adhesion molecules. Furthermore, these processes suppress host antitumor immunity, leading to tumor progression and metastasis. In patients with advanced gastric cancer, most cytokines that enhance or suppress host antitumor immunity appear to have elevated serum and local expression levels. The net cytokine environment fluctuates at various stages of tumor development. In conclusion, a more detailed understanding of the differential roles of malignant cell-derived and hostderived cytokines at different stages of the malignant process could, consequently, open new avenues for the manipulation of cytokine expression and function in cancer immunotherapy for gastric cancer.

NAT2 polymorphism and gastric cancer susceptibility: a meta-analysis

BACKGROUND AND AIMS

N-acetyltransferase 2 (NAT2) is a polymorphic enzyme that plays an important role in the metabolism of various potential carcinogens. NAT2 can be subdivided into rapid and slow acetylation phenotype according to the different genotypes. Studies investigating the association between NAT2 polymorphisms and gastric cancer risk in humans showed conflicting results. The aim of this study was to conduct a meta-analysis assessing the association of NAT2 acetylation phenotype with risk of gastric cancer.

METHODS

Relevant studies were identified through a search of Embase, ISI Web of Knowledge, Medline and Chinese Biomedicine Database until January 2010. A meta-analysis was conducted to quantitatively summarize association of NAT2 acetylation phenotype with GC susceptibility.

RESULTS

Thirteen studies were included in the present meta-analysis, which described a total of 2,391 gastric cancer cases and 3,237 controls. The combined ORs for NAT2 slow or rapid acetylator and gastric cancer risk were 1.05 (95% CI 0.810-1.35) and 0.96 (95% CI 0.74-1.23), respectively. When stratifying for race and Lauren's classification, results also showed no significant association in genotype distribution between gastric cancer and control.

CONCLUSIONS

No association is found between NAT2 acetylation status and gastric cancer risk in this meta-analysis.

Grb2-associated binder 1 (Gab1) genetic polymorphism, Helicobacter pylori infection, and chronic atrophic gastritis among older adults from Germany

Grb2-associated binder 1 (Gab1) plays an important role in the regulation of cell growth and transformation. A single nucleotide polymorphism (SNP) (rs3805246) in the Gab1 gene has been suggested to be related to the risk of Helicobacter pylori infection and chronic atrophic gastritis (CAG) in a study from Japan. We aimed to assess the associations in a population-based study from Germany. In the baseline examination of ESTHER, a population-based study conducted in Saarland, serum pepsinogen I and II and H. pylori serostatus were measured by ELISA. The Gab1 SNP (rs3805246) was genotyped in 351 serologically defined CAG cases and 351 age- and sex-matched non-CAG controls. A nonsignificant association was observed between the Gab1 SNP and CAG, with an adjusted odds ratio of 1.15 (0.85-1.55) for AA/AG carriers compared to GG carriers. The magnitude of the association did not change when the analysis was restricted to H. pylori seropositive subjects. Furthermore, no significant relation was found between the SNP and H. pylori seropositivity among non-CAG controls. We could not confirm a major association between Gab1 SNP (rs3805246) and the predisposition to H. pylori infection and CAG in this study population from Germany. Further studies with larger sample size are needed to clarify a potential modest effect of Gab1 genetic polymorphisms.

Interleukin-10 -1082 promoter polymorphism and gastric cancer risk in a Chinese Han population

Studies investigating the association between interleukin-10 (IL-10) -1082 promoter polymorphism and gastric cancer risk report conflicting results. Our recent meta-analysis suggests that the IL-10 -1082 promoter polymorphism may be associated with gastric cancer among Asians. The objective of this study was to investigate the association between IL-10 -1082 promoter polymorphism and gastric cancer risk in Chinese Han patients. We extracted the peripheral blood samples in 150 patients with gastric cancer and 150 controls. PCR-RFLP analysis was performed to detect IL-10 -1082 promoter polymorphism in these patients. Patients with gastric cancer had a significantly lower frequency of AA (OR = 0.45, 95% CI = 0.27, 0.76; P = 0.003) than controls. Patients with cardia gastric cancer had a significantly higher frequency of GG (OR = 2.17, 95% CI = 1.08, 4.38; P = 0.03) than those with noncardia gastric cancer. Patients with advanced gastric cancer had a significantly higher frequency of AA (OR = 5.21, 95% CI = 1.71, 15.87; P = 0.004) than those with early gastric cancer. When stratified by the Lauren's classification, histological differentiation of gastric cancer, no statistically significant results were observed. This study suggests that the IL-10 -1082 promoter polymorphism may be associated with gastric cancer in Chinese Han patients, and that difference in genotype distribution may be associated with the location and stage of gastric cancer.

p53 Codon 72 polymorphism and gastric cancer risk in a Chinese Han population

BACKGROUND

studies investigating the association between p53 codon 72 polymorphism and gastric cancer risk report conflicting results. Our recent meta-analysis suggests that the p53 codon 72 polymorphism may be associated with gastric cancer among Asians.

AIM

the objective of this study was to investigate the association between p53 codon 72 polymorphism and gastric cancer risk in Chinese Han patients.

METHODS

we extracted the peripheral blood samples from 150 patients with gastric cancer and 150 control subjects. Polymerase chain reaction-restriction fragment length polymorphism analysis was performed to detect p53 codon 72 polymorphism in these patients.

RESULTS

patients with gastric cancer had a significantly lower frequency of Arg/Arg (odds ratio [OR] = 0.48, 95% confidence interval [95% CI] = 0.28, 0.80; p = 0.005) than control subjects. Patients with cardia gastric cancer had a significantly higher frequency of Pro/Pro (OR = 2.26, 95% CI = 1.12, 4.55; p = 0.02) than those with noncardia gastric cancer. Patients with advanced gastric cancer had a significantly higher frequency of Arg/Arg (OR = 2.66, 95% CI = 1.06, 6.65; p = 0.03) than those with early gastric cancer. When stratified by the Lauren's classification, histological differentiation of gastric cancer, no statistically significant result was observed.

CONCLUSION

this study suggests that the p53 codon 72 polymorphism may be associated with gastric cancer in Chinese Han patients, and that difference in genotype distribution may be associated with the location and stage of gastric cancer.

Polymorphic DNA repair and metabolic genes: a multigenic study on gastric cancer

Risk factors for gastric cancer (GC) include inter-individual variability in the inflammatory response to Helicobacter pylori infection, in the ability of detoxifying DNA reactive species and repairing DNA damage generated by oxidative stress and dietary carcinogens. To evaluate the association between polymorphic DNA repair genes and GC risk, a case-control study including 314 histologically confirmed GC patients and 548 healthy controls was conducted in a GC high-risk area in Tuscany, Italy. Polymorphic variants of base excision repair (APE1-D148E, XRCC1-R194W, XRCC1-R399Q and OGG1-S326C), nucleotide excision repair (XPC-PAT, XPA-23G>A, ERCC1-19007T>C and XPD-L751Q), recombination (XRCC3-T241M) and alkylation damage reversal (MGMT-L84F) were tested for their potential role in the development of GC by using logistic regression models. The same population was also characterised for GSTT1 and GSTM1 variant alleles to search for possible functional interactions between metabolic and DNA repair genotypes by two-way interactions using multivariate logistic models. No significant association between any single DNA repair genotype and GC risk was detected with a borderline association with the XPC-PAT homozygous genotype [odds ratio (OR) =1.42; 95% confidence interval (CI) 0.94-2.17]. Gene-gene interaction analysis revealed combinations of unfavourable genotypes involving either multiple DNA repair polymorphisms or DNA repair and GST-specific genotypes. The combination of the XPC-PAT and the XPA variant alleles significantly increased GC risk (OR=2.15; 95% CI 1.17-3.93, P=0.0092). A significant interaction was also found between the APE1 wild-type genotype and either the single GSTT1 (OR=4.90; 95% CI 2.38-10.11, P=0.0079) or double GSTM1-GSTT1 null (OR=7.84; 95% CI 3.19-19.22, P=0.0169) genotypes or the XPA-mutant allele (OR=3.56; 95% CI 1.53-8.25, P=0.0012). These findings indicate that a complex interaction between host factors such as oxidative stress, antioxidant capacity and efficiency of multiple DNA repair pathways underlies the inter-individual variability in GC risk.

The impact of C-MYC gene expression on gastric cancer cell

The upregulation or mutation of C-MYC has been observed in gastric, colon, breast, and lung tumors and in Burkitt's lymphoma. However, little is known about the role C-MYC plays in gastric adenocarcinoma. In the present study, we intended to investigate the influence of C-MYC on the growth, proliferation, apoptosis, invasion, and cell cycle of the gastric cancer cell line SGC7901 and the gastric cell line HFE145. C-MYC cDNA was subcloned into a constitutive vector PCDNA3.1 followed by transfection in normal gastric cell line HFE145 by using liposome. Then stable transfectants were selected and appraised. Specific inhibition of C-MYC was achieved using a vector-based siRNA system which was transfected in gastric cancer cell line SGC7901. The apoptosis and cell cycles of these clones were analyzed by using flow cytometric assay. The growth and proliferation were analyzed by cell growth curves and colony-forming assay, respectively. The invasion of these clones was analyzed by using cell migration assay. The C-MYC stable expression clones (HFE-Myc) and C-MYC RNAi cells (SGC-MR) were detected and compared with their control groups, respectively. HFE-Myc grew faster than HFE145 and HFE-PC (HFE145 transfected with PCDNA3.1 vector). SGC-MR1, 2 grew slower than SGC7901 and SGC-MS1, 2 (SGC7901 transfected with scrambled control duplexes). The cell counts of HFE-Myc in the third, fourth, fifth, sixth, and seventh days were significantly more than those of control groups (P < 0.05). Those of SGC-MR1, 2 in the fourth, fifth, sixth, and seventh days were significantly fewer than those of control groups (P < 0.05). Cell cycle analysis showed that proportions of HFE-Myc and SGC-MR cells in G0-G1 and G2-M were different significantly with their control groups, respectively (P < 0.05). The apoptosis rate of HFE-Myc was significantly higher than those of control groups (P < 0.05). Results of colony-forming assay showed that the colony formation rate of HFE-Myc was higher than those of control groups; otherwise, the rate of SGC-MR was lower than those of their control groups (P < 0.05). The results of cell migration assay showed that there were no significant differences between experimental groups and control groups (P > 0.05). In conclusion, C-MYC can promote the growth and proliferation of normal gastric cells, and knockdown of C-MYC can restrain the growth and proliferation of gastric cancer cells. It can induce cell apoptosis and help tumor cell maintain malignant phenotype. But it can have not a detectable influence on the ability of invasion of gastric cancer cells.

Inflammation, tumor necrosis factor and Wnt promotion in gastric cancer development

Infection-associated chronic inflammation plays an important role in tumorigenesis, and macrophages are a key player in both inflammation and tumorigenesis. Tumor-associated macrophages accelerate tumorigenesis through the enhancement of angiogenesis, remodeling and the suppression of antitumor immunity. Helicobacter pylori infection induces inflammatory responses, which are closely associated with gastric cancer development. Recent studies using mouse models indicate that activated macrophages in the infected and inflamed gastric mucosa express TNF-alpha, which stimulates the surrounding epithelial cells to promote Wnt signaling activity. Such a promotion of Wnt signaling activity beyond the threshold for tumorigenesis may, therefore contribute to gastric cancer development. Accordingly, it is possible that the TNF-alpha-induced promotion of Wnt signaling is a novel protumorigenic mechanism of inflammation in gastric carcinogenesis.

Association of E-cadherin (CDH1) gene polymorphisms and gastric cancer risk

AIM: To investigate the associations between CDH1 gene polymorphisms and gastric cancer (GC) risk predisposition.

METHODS: We analyzed four CDH1 polymorphisms (+54 T>C, -160 C>A, -616 G>C, -3159 T>C) in an Omani population, by extraction of genomic DNA from the peripheral blood of 192 patients with GC and 170 control participants and performed CDH1 genotyping using DNA sequencing.

RESULTS: CDH1 -160 -AA genotype was associated with an increased risk of GC (OR = 3.6, 95% CI: 1.1-11.8) (P = 0.03). There was no significant association between the other polymorphisms and GC risk. The haplotype analysis of +54 T>C, -160 C>A, -616 G>C, -3159 T>C genotypes revealed that the OR of CCGC and CAGC haplotypes was 1.5 (95% CI: 0.7-3.5) and 1.5 (95% CI: 0.2-3.0), but did not reach statistical significance.

CONCLUSION: The current study suggests that the -160 AA genotype was associated with an increased risk of GC in Oman.

Glutathione S-transferase M1 null genotype associated with gastric cancer among Asians

PURPOSE

The Glutathione S-transferases (GSTs) play multiple roles in the pathogenesis and treatment of cancer. Studies investigating the association between Glutathione S-transferase M1 (GSTM1) null genotype and gastric cancer risk report conflicting results. The purpose of this study was to quantitatively summarize the evidence for such a relationship.

RESULTS

This meta-analysis included 35 studies, which included 4,505 gastric cancer cases and 9,062 controls. The combined results based on all studies showed that the GSTM1 null genotype was associated with an increased risk of gastric cancer (OR = 1.15, 95% confidence interval [CI] = 1.02, 1.29). When stratifying for race, results were similar among Asians (OR = 1.24, 95% CI = 1.07, 1.44) except Caucasians (OR = 1.04, 95% CI = 0.88, 1.24). When stratifying by the location, stage, Lauren's classification, histological differentiation, lymph node metastasis, smoking, and Helicobacter pylori infection of gastric cancer, we observed that patients with diffuse classification had a significantly higher frequency null genotype (OR = 4.80, 95% CI = 1.65,13.94) than those with intestinal classification among Caucasians.

CONCLUSIONS

This meta-analysis suggests that the GSTM1 null genotype may be associated with gastric cancer among Asians.

Genetic polymorphisms in DNA repair genes XPC, XPD, and XRCC4, and susceptibility to Helicobacter pylori infection-related gastric antrum adenocarcinoma in Guangxi population, China

Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with risk of gastric antrum adenocarcinoma (GAA) related to Helicobacter pylori infection. This study, including 361 GAAs and 616 controls without any evidence of tumors, was designed to evaluate the association between the polymorphisms of DNA repair genes XPC Ala499Val (RS#2228000) and Lys939Gln (RS#2228001), XPD Lys751Gln (RS#13181), and XRCC4 Ala247Ser (RS#3734091) and Ser298Asn (RS#1805377), and GAA risk for Guangxi population by means of TaqMan-PCR analysis. Increased risks of GAA were found for individuals with H. pylori positive [odds ratio (OR), 2.48; 95% confidence interval (CI), 1.84-3.33] or cagA positive (OR, 7.34; 95% CI, 5.46-9.87). No differences were observed among the studied groups with regard to the genotype distribution of XPC codons 499 and 939 and of XRCC4 codon 247; but XPD codon 751 genotypes with Gln [ORs (95% CI) were 2.67 (1.98-3.58) and 3.97 (2.64-5.99) for Lys/Gln and Gln/Gln, respectively] and XRCC4 codon 298 genotypes with Asn [ORs (95% CI) were 3.01 (2.21-4.10) and 4.78 (3.24-7.05) for Ser/Asn and Asn/Asn, respectively] increased the risk of GAA. Interestingly, there was an interactive effect between the risk genotypes of these two genes and cagA-positive status in the GAA risk (OR(interact) = 2.05 and 2.08, respectively). However, we did not find the gene-H. pylori-status interaction effects on the risk of GAA (P(interact) > 0.05). The results suggested that the polymorphisms of XPD codon 751 and XRCC4 codon 298 are associated with an increased risk of developing H. pylori-related GAA among Guangxi population.

Association between polymorphisms in interleukin-17A and interleukin-17F genes and risks of gastric cancer

Chronic inflammation is the hallmark of the pathogenesis of Helicobacter pylori-induced gastric cancer. Interleukin (IL)-17A and IL-17F are inflammatory cytokines expressed by a novel subset of CD4+ Th cells and play critical function in inflammation and probably in cancer. We conducted a case-control study including 1,010 gastric cancer patients and 800 healthy controls to assess the association between IL-17A G197A and IL-17F A7488G polymorphisms and risk of gastric cancer. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing. Logistic regression and Cox-proportional hazards analyses were used to evaluate the associations between polymorphisms and gastric cancer susceptibility, clinicopathological features and survival. After adjusted for age and gender, IL-17F 7488GA and GG genotypes were associated with an increased risk of gastric cancer compared with AA genotype [OR 1.51, 95% confidence interval (CI): 1.22-1.87 for GA; OR 1.61, 95% CI: 1.03-2.51 for GG]. Further stratification analyses indicated that the effect of IL-17F 7488GA genotype was noteworthy in gastric cancer patients of noncardia, intestinal type, poorly and moderately differentiated, age older than 40, large tumor size and lymph node metastasis. IL-17A 197AG genotype was associated with increased risk of poorly differentiated, TNM I/II, age of 40-65-year subtypes of gastric cancer, but not with total gastric cancer risk (p = 0.098). No significant relationship was observed between polymorphisms and survival of gastric cancer patients. These findings suggest that polymorphism of IL-17F 7488 involved in susceptibility to gastric cancer, which also influenced certain subtypes according to clinicopathological features, whereas IL-17A 197 may be less relevant.

Interleukin10 -592 promoter polymorphism associated with gastric cancer among Asians: a meta-analysis of epidemiologic studies

PURPOSE

Studies investigating the association between interleukin10 (IL10) -592 promoter polymorphism and gastric cancer risk report conflicting results. The objective of this study was to quantitatively summarize the evidence for such a relationship.

METHODS

Two investigators independently searched the MEDLINE and Embase databases. This meta-analysis included ten case-control studies, which included 1,715 gastric cancer cases and 2,783 controls.

RESULTS

The combined results based on all studies showed that there was no significant difference in genotype distribution (AA odds ratio [OR] = 0.88, 95% confidence interval [CI] = 0.66, 1.18; AC OR = 1.09, 95% CI = 0.95, 1.24; CC OR = 1.03, 95% CI = 0.89, 1.18) between gastric cancer and noncancer patients. When stratifying for race, the results were similar, except that patients with gastric cancer had a significantly lower frequency of AA (OR = 0.67, 95% CI = 0.52, 0.87) and a higher frequency of AC (OR = 1.34, 95% CI = 1.07, 1.68) than noncancer patients among Asians. When stratifying by the location of gastric cancer, we found that patients with cardia gastric cancer had a significantly lower frequency of AA (OR = 0.41, 95% CI = 0.20, 0.84) than those with noncardia gastric cancer among Caucasians. When stratifying by Lauren's classification of gastric cancer, we found that patients with diffuse gastric cancer had a significantly higher frequency of AA (OR = 1.91, 95% CI = 1.07, 3.41) than those with intestinal gastric cancer among Caucasians.

CONCLUSIONS

This meta-analysis suggests that the IL10 -592 promoter polymorphism may be associated with gastric cancer among Asians, and that differences in genotype distribution may be associated with the location and Lauren's classification of gastric cancer.

Genetic traits for the persistence of Helicobacter pylori infection

Helicobacter pylori infection elevates the risk of gastric diseases, including peptic ulcer and gastric cancer. Persistent infection is the first step to induce H. pylori-induced multistage diseases. Although the roles of genetic traits on persistent infection have not yet been elucidated, some individuals escape from persistent infection. Possible favorable conditions for H. pylori seem to be low acid secretion, reduced innate immune responses, and easier binding to gastric epithelial cells. IL-1β and TNF-α inhibit acid secretion. The genetic polymorphisms associated with both molecules have the potential to be the genetic traits underlying persistent infection. Functional polymorphisms associated with innate immune responses could also be involved with the genetic traits, but no polymorphisms with consistent associations have been identified so far. The polymorphisms associated with molecules for adhesion to epithelial cells are candidates of genetic traits, but more research is needed.

CDH1 C-160A promoter polymorphism and genetic susceptibility to gastric cancer: a meta-analysis

AIM: To investigate the relationship between E-cadherin (CDH1) gene C-160A promoter polymorphism and genetic susceptibility to gastric cancer.

METHODS: Chinese biomedicine disc (CBM), Wanfang database, China National Knowledge Infrastructure (CNKI) and PubMed were searched for published case-control studies investigating the association between CDH1 C-160A promoter polymorphism and susceptibility to gastric cancer. The odds ratio was calculated to evaluate the genotypes of gastric cancer patients and control subjects. Fixed or random effect models were selected for pooled odds ratio calculation. Publication bias was assessed. All statistical analyses were conducted with Stata 10.0 software.

RESULTS: A total of 14 case-control studies involving 3 144 gastric cancer patients and 4 221 controls were analyzed in the study. Compared with the wild-type genotype (homozygote CC), the pooled odds ratio [and 95% confidence interval (CI)] for CA and AA genotypes was 0.98 (0.84-1.15). In the population subgroup analysis, the odds ratios for Asian and Caucasian populations were 0.92 (0.81-1.04) and 1.21 (0.88-1.67), respectively.

CONCLUSION: CDH1 C-160A promoter polymorphism is not associated with genetic susceptibility to gastric cancer.

Association between dietary heterocyclic amine levels, genetic polymorphisms of NAT2, CYP1A1, and CYP1A2 and risk of stomach cancer: a hospital-based case-control study in Japan

BACKGROUND

Although the associations between grilled (broiled) or barbecued meats or fish intake and stomach cancer risk have been investigated, the evidence implicating heterocyclic amine (HCA) intake as a cause of stomach cancer is limited. We conducted a case-control study to investigate the association between HCA intake and stomach cancer risk. We also investigated the possible effect of genetic polymorphisms of NAT2, CYP1A1, and CYP1A2 on stomach cancer.

METHODS

HCA exposure data were assessed using a self-administered food-frequency questionnaire, and estimated HCA intake was verified by measuring 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) values in human hair. A total of 149 cases and 296 controls were included in the analyses. Odds ratios (ORs) were calculated, using conditional logistic regression analysis, to compare intake levels between the first and third tertiles.

RESULTS

Results showed no statistically significant increase in the risk of stomach cancer with respect to total HCA intake (OR, 1.11; 95% confidence interval [CI], 0.36, 3.49), or with respect to the intake of individual HCAs; namely, PhIP, 2-amino-3, 4-dimethylimidazo[4,5-f]quinoline (MeIQ), and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). Genetic polymorphisms of NAT2, CYP1A1, and CYP1A2 did not influence the association of HCA intake with stomach cancer.

CONCLUSION

In the present study, with a limited sample size of subjects with low HCA exposure, no association was found between HCA intake and stomach cancer, nor was there any evidence of any influence by genetic polymorphisms of NAT2, CYP1A1, and CYP1A2 on the risk of stomach cancer.

Methylenetetrahydrofolate reductase C677T and A1298C polymorphisms and gastric cancer: a meta-analysis

BACKGROUND AND AIMS

Case/control studies that investigated the association between gastric cancer and the MTHFR C677T and A1298C polymorphisms so far have provided controversial results. To clarify the effect of MTHFR polymorphisms on the risk of gastric cancer, a meta-analysis was performed.

METHODS

We performed a computerized search of the PubMed database for relevant reports before September 2009. No language restrictions were added. The associated literature was acquired through a deliberate retrieval strategy and selected based on the established inclusion criteria for publications.

RESULTS

The studies provided 4070/6462 cases/controls for C677T and 1923/3561 cases/controls for A1298C. There was significant heterogeneity (p = 0.015, I(2) = 44.0%) among the 22 studies, and the RE model showed that the C677T allele T was associated with a 17.3% increased risk of gastric cancer compared with the allele C (RE OR = 1.173 [1.051-1.274]). Results from the subgroup analysis showed an increased risk in Asians (fixed-effect, FE OR 1.277 [1.179-1.382]), but not in Caucasians (random-effect, RE OR 1.194 [0.866-1.646]). The contrast of homozygotes (TT vs. CC) produced significant results in Asians (FE OR 1.611 [1.366-1.901]), whereas, in Caucasians, it was not significant (RE OR 1.385 [0.754-2.544]). In regard to the A1298C polymorphism, there was no heterogeneity among the 11 studies comparing the C vs. the A allele (p = 0.352, I(2) = 9.7%), but no significant association was detected.

CONCLUSIONS

The evidence from our meta-analysis supports that TT genotype of MTHFR C677T polymorphism contributes to susceptibility to gastric cancer, but no significant association was detected for CC genotype of MTHFR A1298C.

MBP-1 suppresses growth and metastasis of gastric cancer cells through COX-2

The c-Myc promoter binding protein 1 (MBP-1) is a transcriptional suppressor of c-myc expression and involved in control of tumorigenesis. Gastric cancer is one of the most frequent neoplasms and lethal malignancies worldwide. So far, the regulatory mechanism of its aggressiveness has not been clearly characterized. Here we studied roles of MBP-1 in gastric cancer progression. We found that cell proliferation was inhibited by MBP-1 overexpression in human stomach adenocarcinoma SC-M1 cells. Colony formation, migration, and invasion abilities of SC-M1 cells were suppressed by MBP-1 overexpression but promoted by MBP-1 knockdown. Furthermore, the xenografted tumor growth of SC-M1 cells was suppressed by MBP-1 overexpression. Metastasis in lungs of mice was inhibited by MBP-1 after tail vein injection with SC-M1 cells. MBP-1 also suppressed epithelial-mesenchymal transition in SC-M1 cells. Additionally, MBP-1 bound on cyclooxygenase 2 (COX-2) promoter and downregulated COX-2 expression. The MBP-1-suppressed tumor progression in SC-M1 cells were through inhibition of COX-2 expression. MBP-1 also exerted a suppressive effect on tumor progression of other gastric cancer cells such as AGS and NUGC-3 cells. Taken together, these results suggest that MBP-1-suppressed COX-2 expression plays an important role in the inhibition of growth and progression of gastric cancer.

Association between cytokine gene polymorphisms and gastric precancerous lesions: systematic review and meta-analysis

Polymorphisms within interleukin-1 (IL1) and tumor necrosis factor alpha (TNFA) gene clusters are associated with an increased risk of gastric cancer. However, their role in gastric precancerous lesions remains poorly understood. Our objective was to perform a meta-analysis of studies addressing the association between IL1B-511, IL1RN variable number of tandem repeat, and TNFA-308 gene polymorphisms and gastric precancerous lesions, including original data from Portugal and Mozambique. Published studies on the association between these cytokine gene polymorphisms and gastric precancerous lesions were identified by systematic review, and estimates of the association were combined using random-effects meta-analysis taking into account new data obtained from Portuguese volunteer shipyard workers (n = 215) and Mozambican dyspeptic patients (n = 96) who underwent endoscopic and pathologic evaluation following the same protocol. Odds ratio (OR) estimates for intestinal metaplasia were 2.83 [95% confidence interval (95% CI), 1.15-6.96] for the IL1RN*22 genotype, 1.86 (95% CI, 1.03-3.36) for IL1B-511 T carriers, and 0.59 (95% CI, 0.12-3.04) for the TNFA-308*AA genotype in the Portuguese sample. All Mozambican subjects with intestinal metaplasia were T carriers for IL1B-511 and none had the 2 allele for IL1RN. In meta-analysis, IL1RN*22 genotype was associated with an increased risk of gastric precancerous lesions (22 versus LL: OR, 2.27; 95% CI, 1.40-3.70; I(2) = 26.4%; 12 studies). No such association was found for the IL1B-511 (TT versus CC: OR, 1.34; 95% CI, 0.87-2.07; I(2) = 65.7%; 13 studies) or TNFA-308 genotypes (AA versus GG: OR, 0.93; 95% CI, 0.35-2.43; I(2) = 0.0%; 7 studies). The IL1RN*22 genotype seems to consistently increase the risk of gastric precancerous lesions, supporting a role for this polymorphism in the early stages of gastric carcinogenesis.

The influence of TXNDC5 gene on gastric cancer cell

BACKGROUND

TXNDC5 (thioredoxin domain containing 5) is over-expressed in tumors of the cervix, uterus, stomach and lung. However, not much is known about the functional roles of TXNDC5 gene in gastric adenocarcinoma. In the present study, we intend to investigate the effects of TXNDC5 on the growth, proliferation, apoptosis, invasion and cell cycle of the gastric cancer cell line MKN45 and normal gastric cell line HFE145.

METHODS

TXNDC5 cDNA was inserted into a constitutive vector pcDNA3.1 followed by transfection into normal gastric cell line HFE145 using liposome. Then, stable transfectants were selected and appraised. Specific silencing of TXNDC5 gene was achieved using a vector-based short interference RNAs (siRNA) system in gastric cancer cell line MKN45. The growth and proliferation were analyzed by cell growth curves and colony-forming assay, respectively. The apoptosis and cell cycles of these clones were analyzed using flow cytometry. The invasion of these cells was analyzed by cell migration assay. The TXNDC5 stable expression cell lines (HFE-TXNDC5) and TXNDC5 RNAi cell lines (MKN-SR1,2) were detected and compared with their control groups, respectively.

RESULTS

HFE-TXNDC5 grew faster than HFE145 and HFE-PC(HFE145 transfected with pcDNA3.1 vector). MKN-SR1 grew slower than MKN45 and MKN-SS1,2 (MKN45 transfected with scrambled control duplexes). The cell counts of HFE-TXNDC5 in the fifth, sixth and seventh days were significantly higher than those of control groups (P < 0.05). The cell counts of MKN-SR1 in the fifth, sixth and seventh days were significantly lower than those of control groups (P < 0.05). Cell cycle analysis showed that there were significant differences in proportions of G0-G1 and G2-M phase between HFE-TXNDC5, MKN-SR1 cells and their control groups, respectively (P < 0.05). The apoptosis rate of HFE-TXNDC5 was significantly lower than that of control groups (P < 0.05). The results of colony-forming assay showed that the colony formation rate of HFE-TXNDC5 was higher than those of control groups, otherwise the rate of MKN-SR1 were lower than those of their control groups (P < 0.05). The results of cell migration assay showed that the migration rate of HFE-TXNDC5 were significantly higher than that of its control group. Conversely, the migration rate of MKN-SR1 was significantly lower than that of its control group (P < 0.05).

CONCLUSION

TXNDC5 can promote the growth and proliferation of gastric cells. Silencing of TXNDC5 can restrain the growth and proliferation of gastric cancer cells. The gene can enhance the capability of invasion of gastric cancer cells. In some respects, TXNDC5 could be thought as a tumor-enhancing gene in gastric cancer.

Interleukin-10-819 Promoter Polymorphism Associated with Gastric Cancer among Asians

Studies investigating the association between interleukin-10-819 promoter polymorphism and gastric cancer risk report conflicting results. This study aimed to summarize quantitatively the evidence for such a relationship. Two investigators independently searched the Medline (January 1966 – January 2009) and Embase (January 1980 – January 2009) databases for eligible studies to be included in a meta-analysis. Six case-control studies, which included 681 gastric cancer cases and 1621 control subjects were selected. Combined results for all studies showed that there was no significant difference in genotype distribution (TT, TC or CC) between gastric cancer patients and control subjects. When stratifying for race, results were similar except that Asian patients with gastric cancer had a significantly lower frequency of TT and a higher frequency of TC than Asian control subjects. When stratifying by location and Lauren's classification of gastric cancer, there was no significant difference in genotype distribution between patients with gastric cancer and control subjects. This meta-analysis suggests that the interleukin-10-819 promoter polymorphism may be associated with gastric cancer in Asians.

The discrepancy between genetic polymorphism of p53 codon 72 and the expression of p53 protein in Helicobacter pylori-associated gastric cancer in Korea

The p53 gene has been referred to as 'the guardian of the genome' because it controls apoptosis and cell cycle arrest. The purpose of this study was to evaluate the association of p53 codon 72 genetic polymorphism and the p53 immunohistochemistry with Helicobacter pylori-associated gastroduodenal diseases, including gastric cancer. This study included 1,852 subjects: controls and patients with gastric cancer, dysplasia, benign gastric ulcers, and duodenal ulcers (DU). Biallelic polymorphism was genotyped by restriction fragment length polymorphism. Immunohistochemical analysis for the detection of mutant type p53 expression was performed. The frequency of the Pro/Pro allele of the p53 codon 72 was higher in the patients with H. pylori-positive dysplasia than in controls (OR: 2.3, 95% CI: 1.3-4.3), but it was less frequent among patients with a H. pylori-positive DU (OR: 0.5, 95% CI: 0.3-0.8). However, there was no significant association with gastric cancer, including the location, stage, or histological type of gastric cancer. Expression of a mutant type of p53 protein was detected in 6.3% of dysplastic tissues and 26.5% of cancerous tissues compared 0% in the controls. Positive expression was higher in the intestinal type of cancer (34.9%) than in the diffuse type (15.0%; P = 0.001). These results suggest that genetic polymorphism of p53 codon 72 played a role in the determination of H. pylori-associated gastroduodenal diseases, but p53 immunostaining did not correlate with those of the p53 genetic polymorphism analysis.

Glutathione-S-transferase (GSTM1, GSTT1) and the risk of gastrointestinal cancer in a Korean population

AIM: To evaluate the association of glutathione S-transferase mu (GSTM1) and glutathione S-transferase theta (GSTT1) null genotypes with the risk of gastric cancer (GC) and colorectal cancer (CRC) in a South Korean population.

METHODS: We conducted a population-based, large-scale case-control study including 2213 GCs, 1829 CRCs, and 1699 controls. Null and non-null genotypes of GSTM1 and GSTT1 were determined using real-time PCR.

RESULTS: The null genotypes of GSTM1 and GSTT1 were not significantly associated with elevated risk of gastric (OR = 1.070, 95% CI = 0.935-1.224; OR = 1.101, 95% CI = 0.963-1.259, respectively) or colorectal cancer (OR = 1.065, 95% CI = 0.923-1.228; OR = 1.041, 95% CI = 0.903-1.200, respectively). The frequency of the combined null GST genotype was not different between the two cancer groups and controls. Moreover, smoking, drinking, and age did not modify the association between these genotypes and the risk of gastric or colorectal cancer.

CONCLUSION: GSTM1 and GSTT1 null genotypes were not associated with increased risk of GC or CRC in Koreans.

LTA 252GG and GA genotypes are associated with diffuse-type noncardia gastric cancer risk in the Japanese population

BACKGROUND

There are limited numbers of reports on the association of lymphotoxin-alpha (LTA) genotypes with gastric cancer.

METHODS

A nested case-control study was carried out in the longitudinal cohort of atomic bomb survivors using stored sera before diagnosis (mean, 2.3 years) and blood cells. Enrolled were 287 cases with noncardia gastric cancer of diffuse and intestinal types and three controls per case selected from cohort members matched on age, gender, city, and time and type of serum storage and counter-matched on radiation dose.

RESULTS

LTA 252GG and GA genotypes were associated with the prevalence of Helicobacter pylori IgG seropositivity and higher antibody titer against H. pylori cytotoxin-associated gene A (CagA) protein in controls and they were an independent risk factor for noncardia gastric cancer of diffuse type (RR = 2.8 (95% CI: 1.3-6.3), p = .01, and RR = 2.7 (95% CI: 1.5-4.8), p < .001), but not for intestinal type, after adjusting for H. pylori IgG seropositivity, CagA antibody titers, chronic atrophic gastritis, smoking, and radiation dose. Cessation of smoking (RR = 0.4 (95% CI: 0.2-0.7), p < .001) and never smoking (RR = 0.4 (95% CI: 0.3-0.6), p < .001) were both protective for future noncardia gastric cancer. Radiation dose was associated with noncardia gastric cancer in subjects with both the LTA 252G-allele and never smoking/quit smoking histories (RR = 3.8 (95% CI: 1.7-5.9), p = .009).

CONCLUSION

The LTA 252 genotype is associated with noncardia gastric cancer of diffuse type in Japan and interacted with radiation dose.

Genetic variation in a4GnT in relation to Helicobacter pylori serology and gastric cancer risk

BACKGROUND

Helicobacter pylori, a known risk factor of gastric cancer, rarely colonize the deeper portion of normal gastric glands, where the mucus is rich in alpha-1,4-linked N-acetylglucosamine capped O-glycans, that strongly inhibit H. pylori growth in vitro.

MATERIALS AND METHODS

We investigated the association between genetic variation in the O-glycan transferase encoding gene (a4GnT) and H. pylori infection and gastric cancer risk using a Polish population-based case-control study (273 gastric cancer patients and 377 controls).

RESULTS

A haplotype at the rs2622694-rs397266 locus was associated with H. pylori infection, with the A-A haplotype associated with a higher risk compared with the most frequent G-G haplotype (odds ratio 2.30; 95% confidence interval 1.35-3.92). The association remained significant after correction for multiple tests (global p value: nominal 0.002, empirical 0.045). Neither this haplotype nor the tagSNPs were associated with overall gastric cancer risk.

CONCLUSION

a4GnT genetic variation may be relevant to H. pylori infection, but not to gastric cancer risk.

Effects of dietary factors and the NAT2 acetylator status on gastric cancer in Koreans

Environmental dietary carcinogens and genetic polymorphisms in metabolic enzymes have been reported to be the risk factors for gastric cancer. This study was undertaken to investigate the effects of the diet, the N-acetyltransferase (NAT) 2 acetylation status and their interaction on gastric cancer risk. The study population consisted of 471 gastric cancer patients and 471 age- and sex-matched control subjects. NAT2 genotypes were identified using single-nucleotide primer extension reaction methods. Thirty-one alleles related to 12 polymorphism sites were assayed in this study. Significantly increased odds ratios were observed in former smokers (OR = 2.39, 95% CI = 1.57-3.62), heavy drinkers (OR = 1.28, 95% CI = 1.06-1.55) and individuals who eat well-done meat (OR = 1.24, 95% CI = 1.09-1.41). The odds ratios (95% CI) for high intake of kimchi, stews and soybean paste were 3.27 (2.44-4.37), 1.96 (1.50-2.58) and 1.63 (1.24-2.14), respectively. The NAT2 genotype alone was not associated with gastric cancer risk. A significant gene-environment interaction was observed between environmental carcinogens and NAT2 genotypes. The odds ratios for kimchi, stews and soybean paste were higher in slow/intermediate acetylators than in rapid acetylators. The odds ratios for slow/intermediate acetylators were 2.28 (95% CI: 1.29-4.04) for light smokers and 3.42 (95% CI: 2.06-5.68) for well-done meat intake. The NAT2 acetylator genotype may be an important modifier of the effects of environmental factors on gastric cancer risk.

Polymorphisms of thymidylate synthase in the 5'- and 3'-untranslated regions and gastric cancer

Studies investigating the association of polymorphisms in the 5'-untranslated regions (5'UTR) and 3'-untranslated regions (3'UTR) of thymidylate synthase with gastric cancer susceptibility and sensitivity to fluoropyrimidine-based chemotherapy report conflicting results. The objective of this study was to quantitatively summarize the evidence for such a relationship. This meta-analysis included ten studies, which included 1,730 gastric cancer cases and 1,843 controls. The combined results based on all studies showed that there was no significant difference in genotype distribution of 5'UTR or 3'UTR between gastric cancer and noncancer patients. When stratifying for race, we found that: (1) among Asians, patients with gastric cancer had significantly higher frequency of 2R/2R of 5'UTR than did noncancer patients, and (2) among Caucasians, patients with gastric cancer had significantly lower frequency of ins6/ins6 and higher frequency of ins6/del6 of 3'UTR than did noncancer patients. No significantly different response rate or survival of gastric cancer with fluoropyrimidine-based chemotherapy were observed with genotype distribution of 5'UTR or 3'UTR among Caucasians or Asians. This meta-analysis suggests that polymorphisms in the 5'UTR and 3'UTR of thymidylate synthase may be associated with gastric cancer susceptibility, but are not correlated with sensitivity of gastric cancer to fluoropyrimidine-based chemotherapy.

Cell proliferation-related genetic polymorphisms and gastric cancer risk: systematic review and meta-analysis

Apart from Helicobacter pylori infection and lifestyle factors, host genetic susceptibility has been suggested to contribute to individual variation in gastric cancer risk as well. Aiming to evaluate the associations between host cell proliferation-related genetic polymorphisms and gastric cancer susceptibility, we reviewed the related studies published until 15 September 2008 and quantitatively summarized the associations of the most widely studied polymorphisms (TP53 Arg72Pro, L-myc EcoRI) using meta-analysis. Fifty-five eligible studies were included in this review. Twenty-three polymorphisms significantly related to gastric cancer risk in at least one study were identified. Polymorphisms determining higher levels of growth factors, which are important for tissue repair, were recently observed to be associated with reduced risk of gastric cancer. In the meta-analysis, TP53 72Pro was associated with increased risk of diffuse gastric cancer among Asians (OR, 1.44; 95% CI, 1.04-1.99), but decreased risk of intestinal gastric cancer among Caucasians (OR, 0.56; 95% CI, 0.36-0.89). This review suggests that cell proliferation-related genetic polymorphisms could be candidate biomarkers of gastric cancer risk, but current evidence for the use for risk stratification is still very limited. Modestly significant associations in meta-analyses stratified by population or type of gastric cancer may be observed by chance because of the limited number of studies and small sample size. Larger studies are warranted to clarify the effect of cell proliferation-related genetic polymorphisms on gastric carcinogenesis.

Role of xenobiotic-metabolizing enzyme gene polymorphisms and interactions with environmental factors in susceptibility to gastric cancer in Kashmir Valley

BACKGROUND

Kashmir Valley has elevated incidence rate of gastric cancer (GC) and several environmental, host genetic factors have been suspected for it. Xenobiotic carcinogen exposure and interindividual differences in its cellular metabolism may modulate susceptibility to GC.

AIM OF THE STUDY

The aim of this study is to investigate the role of genetic variants of xenobiotic-metabolizing genes with susceptibility to GC in Kashmir Valley.

METHODS

A case-control study was performed in 303 subjects (108 GC and 195 healthy controls) to analyze the association of polymorphisms in GSTM1, GSTT1, GSTP1, GSTM3, CYP1A1, and CYP2E1 genes in susceptibility to GC in Kashmir Valley. All subjects were genotyped through polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

GSTM1null and CYP2E1c1c2 genotypes imparted risk for GC (odds ratio [OR] = 1.98, 95% confidence interval [95%CI] = 1.22-3.21, P = 0.006 and OR = 2.56, 95%CI = 1.25-5.25, P = 0.010, respectively). GSTM3AB genotype/B allele was found to be associated with low risk for GC. Smokers and high salted tea consumers themselves were at higher risk for GC (OR = 8.98, 95%CI = 5.16-15.62, P = 0.0001 and OR = 14.78, 95%CI = 8.02-27.23, P = 0.0001, respectively). Cancer risk was further enhanced in smokers with the GSTM1null genotype.

CONCLUSION

The results suggest that GSTM1null, GSTM3AB, and CYP2E1c1c2 genotypes modulate the risk of GC whereas GSTM1null genotypes enhance the risk of GC for smokers in the Kashmir population.

The activated Notch1 signal pathway is associated with gastric cancer progression through cyclooxygenase-2

Gastric carcinoma is one of the most common cancers and lethal malignancies worldwide. Thus far, the regulatory mechanisms of its aggressiveness are still poorly understood. To understand the pathogenesis and to develop new therapeutic strategies, it is essential to dissect the molecular mechanisms that regulate progression of gastric cancer. Herein, we sought to address whether Notch1 signal pathway is involved in the control of progression in gastric cancer. We found that expression of Notch ligand Jagged1 was correlated with aggressiveness of human gastric cancer. Patients with Jagged1 expression in gastric cancer tissues had a poor survival rate compared with those without Jagged1 expression. The Notch1 receptor intracellular domain (N1IC), the activated form of Notch1 receptor, promoted the colony-forming ability and xenografted tumor growth of human stomach adenocarcinoma SC-M1 cells. Migration and invasion abilities of SC-M1 cells were enhanced by N1IC. Furthermore, N1IC and C promoter-binding factor 1 (CBF1) bound to cyclooxygenase-2 (COX-2) promoter and elevated COX-2 expression in SC-M1 cells through a CBF1-dependent manner. The colony-forming, migration, and invasion abilities enhanced by N1IC were suppressed in SC-M1 cells after treatment with the COX-2 inhibitor NS-398 or knockdown of COX-2. These cellular processes inhibited by Notch1 knockdown were restored by prostaglandin E(2) or exogenous COX-2. Taken together, these results suggest that activation of Notch1 signal pathway promotes progression of gastric cancer, at least in part through COX-2.

Transcriptome dissection of gastric cancer: identification of novel diagnostic and therapeutic targets from pathology specimens

Gastric cancer is the fourth most common malignancy in the world, and mortality due to gastric cancer is second only to that from lung cancer. 'Transcriptome dissection' is a detailed analysis of the entire expressed transcripts from a cancer, for the purpose of understanding the precise molecular mechanism of pathogenesis. Serial analysis of gene expression (SAGE) is a suitable technique for performing transcriptome dissection. Gastric cancers of different stages and histology were analyzed on SAGE, and one of the largest gastric cancer SAGE libraries in the world was created (GEO accession number GSE 545). Through SAGE, many candidate genes have been identified as potential diagnostic and therapeutic targets for the treatment of gastric cancer. Regenerating islet-derived family, member 4 (Reg IV) participated in 5-fluorouracil (5-FU) resistance and peritoneal metastasis, and its expression was associated with an intestinal phenotype of gastric cancer and with endocrine differentiation. GW112 expression correlated with advanced tumor stage. Measurement of Reg IV and GW112 levels in sera indicated a sensitivity of 57% for detection of cancer. SPC18 participated in tumor growth and invasion through transforming tumor growth factor-alpha upregulation. Palate, lung, and nasal epithelium carcinoma-associated protein (PLUNC) was a useful marker for gastric hepatoid adenocarcinoma. Expression of SOX9, HOXA10, CDH17, and loss of claudin-18 expression were associated with an intestinal phenotype of gastric cancer. Information obtained from transcriptome dissection greatly contributes to diagnosis and treatment of gastric cancer.

Functional polymorphism of NFKB1 promoter may correlate to the susceptibility of gastric cancer in aged patients

BACKGROUND

Activated nuclear factor-kappaB (NF-kappaB) is associated reportedly with the pathogenesis of numerous malignancies. This study investigated whether a common insertion (ins)/deletion (del) polymorphism (-94 ins/del ATTG) in the NFKB1 promoter is associated with susceptibility to gastric cancer and its tumor behavior.

METHODS

Blood samples from 182 gastric cancer patients and 116 controls were examined by polymerase chain reaction-based genotyping. Allelotype and genotype (polymorphism) of NFKB1 promoter in gastric cancer patients were analyzed with controls and patients' clinicopathologic factors to evaluate their association using a multivariate analytical model.

RESULTS

The mean ages of patients and controls were 65.7 +/- 12.8, and 64.9 +/- 8.8 years old, respectively. Sex ratios (male to female) were 2.7:1 and 2.2:1, respectively. Insertion allelotype, genotypes with ins/ins, as well as ins allele carrier (ins/ins+ ins/del) were significantly greater in gastric cancer patients than in controls, especially in patients >65 years old, but not in younger patients. The polymorphism did not correlate with clinicopathologic factors and patient survival.

CONCLUSION

NFKB1 could be a susceptible gene for gastric cancer and its functional polymorphism in promoter is associated with the risk of gastric cancer, particularly in aged patients.

Combined polymorphism analysis of glutathione S-transferase M1/G1 and interleukin-1B (IL-1B)/interleukin 1-receptor antagonist (IL-1RN) and gastric cancer risk in an Omani Arab Population

BACKGROUND

Host genetics have been implicated in gastric cancer carcinogenesis. Polymorphisms of glutathione S-transferase (GST) M1 and G1 and of interleukin-1B (IL-1B) and interleukin-1 receptor antagonist (IL-1RN) were shown to increase gastric cancer predisposition in several studies. To our knowledge, this is the first report on the combined analysis of polymorphisms GSTM1/G1 and IL-1B/IL-1RN genes in gastric adenocarcinoma.

METHODS

Genomic DNA was extracted from peripheral blood of 107 control subjects and 107 gastric cancer patients. Analysis for the GSTM1 and GSTT1 gene polymorphisms was performed by multiplex polymerase chain reaction. The DNA samples were analyzed using the TaqMan allelic discrimination test for the polymorphism of IL-1B at positions-31. The variable number of tandem repeats of IL-1RN was genotyped using polymerase chain reaction followed by agarose gel electrophoresis.

RESULTS

There were no statistically significant associations between the GSTM1/G1 or IL-1B-31 genes and gastric cancer risk. There was a statistical association between the presence of the IL-1RN*2 allele and gastric cancer (odds ratio 2.2, 95% confidence interval=1.2-3.7, P=0.01). Combined analysis showed that a combination of the null GSTM1 genotype and carriers of IL-1RN*2 was associated with a statistically significant correlation with gastric cancer (odds ratio=3.6, 95% confidence interval=1.4-9.4, P=0.008).

CONCLUSIONS

The current study suggests that the individual variation in both the cellular inflammatory modulator IL-1RN and the antioxidative property of GSTM1 may predispose individuals to an increased risk of gastric cancer.

Role of host interleukin 1beta gene (IL-1B) and interleukin 1 receptor antagonist gene (IL-1RN) polymorphisms in clinical outcomes in Helicobacter pylori-positive Turkish patients with dyspepsia

BACKGROUND

Helicobacter pylori infection leads to different clinical outcomes depending on both host and bacterial factors. In a recent study, we identified H. pylori cagE and babA2 genotypes as independent predictors of duodenal ulcer (DU) and gastric cancer (GC) in dyspepsia patients, but no previous studies have examined the role of host-related genetic factors in Turkey. This time our aim was to evaluate whether polymorphisms of the interleukin 1B (IL-1B) and the interleukin 1 receptor antagonist (IL-1RN) genes are important factors in the differential expression of gastroduodenal diseases in H. pylori-positive dyspepsia patients.

METHODS

Ninety-three H. pylori-positive patients, 30 with nonulcer dyspepsia (NUD), 30 with DU, and 33 with GC, were investigated. The IL-1B-511 and IL-1B-31 biallelic polymorphisms, and the IL-1RN intron 2 variable number tandem repeat were genotyped by polymerase chain reaction and single-strand confirmation polymorphism analysis.

RESULTS

The IL-1RN-1/1 genotype was significantly more prevalent among patients with NUD than among those with GC (chi(2) = 9.270; P = 0.002), and the IL-1RN-1/2 genotype was significantly more common in patients with GC (chi(2) = 6.01; P = 0.014). Multivariate regression analysis showed that cagE, babA2, and IL-1RN-1/2 genotypes were independent predictors of GC, but when patients with benign disorders were grouped together (NUD + DU) and compared with patients with GC, regression analysis disclosed that babA2 (P = 0.000) and IL-1B-31 gene polymorphisms (CC or CT) (P = 0.01) were the only independent markers of GC.

CONCLUSIONS

When analyzed together with host genetic factors, the well established bacterial risk factor babA2 seems to be the most important predictor of malignant disorders, and the presence of the IL-1B-31TT genotype emerges as a protective factor against them.

Impact of pepsinogen C polymorphism on individual susceptibility to gastric cancer and its precancerous conditions in a Northeast Chinese population

PURPOSE

Human pepsinogen C (PGC) is an aspartic protease produced specifically by the gastric mucosa, and is considered as a mature marker of gastric epithelium. This study examined the contributions of PGC polymorphisms and the Helicobacter pylori (H. pylori) infection to the risk of gastric cancer (GC), and its precancerous conditions in a Northeast Chinese population.

METHODS

The PGC insertion/deletion polymorphism was evaluated by polymerase chain reaction analysis, followed by direct DNA sequencing in 564 cases of GC, atrophic gastritis (AG), gastric ulcer (GU) and superficial gastritis (as control). All cases were frequency-matched 1:1 by gender and age (+/-5). H. pylori infection was identified by serum anti-H. pylori IgG measurement through enzyme-linked immunosorbent assay.

RESULTS

Patients with a homozygous PGC allele 1 genotype had a significant risk of AG [adjusted odds ratio (OR) 3.11; 95% confidence interval (CI) 1.44-6.71] or of GC (OR 3.00; 95% CI 1.38-6.51), and a significantly elevated risk of intestinal metaplasia (OR 1.90, 95% CI 1.11-3.27). PGC polymorphism with H. pylori infection increased risk of GU (OR 8.69; 95% CI 1.01-74.69), and AG (OR 11.12; 95% CI 1.37-90.84) or GC (OR 10.61; 95% CI 1.28-87.79) in a super-multiplicative manner. The S value was 5.40, 6.48 and 4.34; and the AP value was 72.09, 7.00 and 69.69%, respectively.

CONCLUSIONS

The PGC gene polymorphism increases an individual's susceptibility to GC and its precancerous conditions. Moreover, the PGC gene polymorphism shows a positive link to H. pylori infection in the development of GC.

Phase I and II enzyme polymorphisms as risk factors for Barrett's esophagus and esophageal adenocarcinoma: a systematic review and meta-analysis

Although several studies have examined the association between phase I/II enzyme polymorphisms and esophageal adenocarcinoma (EAC) and/or Barrett's esophagus (BE), their overall findings remain unclear. We performed a systematic review and meta-analysis to determine whether phase I/II polymorphisms are independent risk factors for either BE or EAC. We employed keyword searches in multiple databases to identify studies published before October 1, 2007. Single-nucleotide polymorphisms (SNPs) examined in > or =3 studies were meta-analyzed to obtain a pooled estimate of effect. Meta-analysis suggested the minor allele for GSTP1 Val(105) conveys modest excess risk (odds ratio [OR](BE)= 1.50, 95% confidence interval [CI] 1.16-1.95; OR(EAC)= 1.20, 95% CI 0.94-1.54). No excess risk was observed with GSTM1 null (OR(BE)= 0.77, 95% CI: 0.56-1.08; OR(EAC)= 1.08, 95% CI: 0.79-1.48), GSTT1 null (OR(BE)= 1.35, 95% CI: 0.91-2.01; OR(EAC)= 0.84, 95% CI: 0.48-1.49), or CYP1A Val(462) (OR(EAC)= 0.89, 95% CI: 0.40-1.97). Insufficient data existed to meta-analyze remaining SNPs. Our review identified GSTP1(Ile105Val) as a possible risk factor for BE and EAC in Caucasian males. No excess risk was observed for other phase I/II polymorphisms with sufficient data to meta-analyze. Additional studies are needed to determine if GSTP1 conveys excess risk in females or non-Caucasians and to evaluate other phase I/II polymorphisms.

Polymorphisms of interleukin-1 and interleukin-2 genes in patients with gastric cancer in Korea

BACKGROUND AND AIM

Interleukin (IL)-1 gene polymorphism has been reported to be associated with the increment of gastric cancer (GC) and the decrement of duodenal ulcers (DU). In addition, IL-2 is known to induce Helicobacter pylori (H. pylori)-associated gastric atrophy, but it is not known whether IL-2 gene polymorphism increases the risk of GC (GC) or peptic ulcer diseases. Therefore, we compared the genotypes of IL-1B, IL-1RN, and IL-2 gene polymorphisms with risk of gastric ulcers (GU), GC, and DU in Korean patients.

METHODS

In total, 116 GU, 122 GC, and 104 DU patients were included consecutively and compared with 100 healthy controls. Polymorphisms of the IL-1B-511/-31 gene, the penta-allelic variable number of tandem repeats of the IL-1RN gene, and the IL-2-330 gene were analyzed by polymerase chain reaction with restriction fragment length polymorphism or confronting two-pair primers methods.

RESULTS

The age-sex-adjusted odds ratios (OR) for the IL-1B-511 T genotype relative to the C/C genotype (OR = 0.82, 95% confidence interval [CI] 0.41-1.65), IL-1RN*2 genotype relative to the L/L genotype (OR = 0.85, 95% CI 0.41-1.78), and IL-2-330 T genotype relative to the G/G genotype (OR = 1.94, 95% CI 0.76-4.96) were not increased in GC. There was also no significant difference in the genotypes of these cytokine polymorphisms between the study group (GU or DU) and control group. In addition, genotypic frequency was not associated with H. pylori positivity and histological type of GC.

CONCLUSION

IL-1B-511, IL-1RN, and IL-2 genetic polymorphisms were not important contributors to the pathogenesis of GU, GC, and DU in Korean patients.

Association between H-RAS T81C genetic polymorphism and gastrointestinal cancer risk: a population based case-control study in China

Background

Gastrointestinal cancer, such as gastric, colon and rectal cancer, is a major medical and economic burden worldwide. However, the exact mechanism of gastrointestinal cancer development still remains unclear. RAS genes have been elucidated as major participants in the development and progression of a series of human tumours and the single nucleotide polymorphism at H-RAS cDNA position 81 was demonstrated to contribute to the risks of bladder, oral and thyroid carcinoma. Therefore, we hypothesized that this polymorphisms in H-RAS could influence susceptibility to gastrointestinal cancer as well, and we conducted this study to test the hypothesis in Chinese population.

Methods

A population based case-control study, including 296 cases with gastrointestinal cancer and 448 healthy controls selected from a Chinese population was conducted. H-RAS T81C polymorphism was genotyped by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) assay.

Results

In the healthy controls, the TT, TC and CC genotypes frequencies of H-RAS T81C polymorphism, were 79.24%, 19.87% and 0.89%, respectively, and the C allele frequency was 10.83%. Compared with TT genotype, the TC genotype was significantly associated with an increased risk of gastric cancer (adjusted OR = 3.67, 95%CI = 2.21–6.08), while the CC genotype showed an increased risk as well (adjusted OR = 3.29, 95%CI = 0.54–19.86), but it was not statistically significant. In contrast, the frequency of TC genotype was not significantly increased in colon cancer and rectal cancer patients. Further analysis was performed by combining TC and CC genotypes compared against TT genotype. As a result, a statistically significant risk with adjusted OR of 3.65 (95%CI, 2.22–6.00) was found in gastric cancer, while no significant association of H-RAS T81C polymorphism with colon cancer and rectal cancer was observed.

Conclusion

These findings indicate, for the first time, that there is an H-RAS T81C polymorphism existing in Chinese population, and this SNP might be a low penetrance gene predisposition factor for gastric cancer.

A systematic review of meta-analyses on gene polymorphisms and gastric cancer risk

BACKGROUND

Individual variations in gastric cancer risk have been associated in the last decade with specific variant alleles of different genes that are present in a significant proportion of the population. Polymorphisms may modify the effects of environmental exposures, and these gene-environment interactions could partly explain the high variation of gastric cancer incidence around the world. The aim of this report is to carry out a systematic review of the published meta-analyses of studies investigating the association between gene polymorphisms and gastric cancer risk, and describe their impact at population level. Priorities on the design of further primary studies are then provided.

METHODS

A structured bibliographic search on Medline and EMBASE databases has been performed to identify meta-analyses on genetic susceptibility to gastric cancer, without restriction criteria. We report the main results of the meta-analyses and we describe the subgroup analyses performed, focusing on the detection of statistical heterogeneity. We investigated publication bias by pooling the primary studies included in the meta-analyses, and we computed the population attributable risk (PAR) for each polymorphism.

RESULTS

Twelve meta-analyses and one pooled-analysis of community based genetic association studies were included, focusing on nine genes involved in inflammation (IL-1beta, IL-1RN, IL-8), detoxification of carcinogens (GSTs, CYP2E1), folate metabolism (MTHFR), intercellular adhesion (E-cadherin) and cell cycle regulation (p53). According to their random-Odds Ratios, individuals carrying one of the IL-1RN *2, IL-1beta -511T variant alleles or homozygotes for MTHFR 677T are significantly at higher risk of gastric cancer than those with the wild type homozygote genotypes, showing high PARs. The main sources of heterogeneity in the meta-analyses were ethnicity, quality of the primary study, and selected environmental co-exposures. Effect modification by Helicobacter pylori infection for subjects carrying the unfavourable variant of IL-1 polymorphisms and by low folate intake for individuals homozygotes for MTHFR 677T allele has been reported, while genes involved in the detoxification of carcinogens show synergistic interactions. Publication bias was observed (Egger test, p = 0.03).

DISCUSSION

The published meta-analyses included in our systematic review focused on polymorphisms having a small effect in increasing gastric cancer risk per se. Nevertheless, the risk increase by interacting with environmental exposures and in combination with additional unfavourable polymorphisms. Unfortunately meta-analyses are underpowered for many subgroup analyses, so additional primary studies performed on larger population and collecting data on environmental and genetic co-exposures are demanded.

Meta-analysis: tumour invasion-related genetic polymorphisms and gastric cancer susceptibility

BACKGROUND

Host genetic susceptibility has been suggested as one of the most important possible explanations for interindividual difference in gastric cancer (GC) risk.

AIM

To evaluate the impact of tumour invasion-related gene polymorphisms, which may be involved in a variety of processes during GC development, such as cell adhesion and angiogenesis, on the risk of GC.

METHODS

We reviewed published studies on tumour invasion-related gene polymorphisms and GC susceptibility until 31 March 2008, and then quantitatively summarized associations of the most widely-studied polymorphism, CDH1 -160C>A, with GC using meta-analysis.

RESULTS

Twenty-seven eligible studies were included in this review. Fourteen polymorphisms significantly related to GC in at least one study were identified. For several polymorphisms, heterogeneous results were observed and associations in opposite directions were seen among Asian and Caucasian populations. In meta-analysis, CDH1 -160C>A showed an inverse association with GC among Asians (OR, 0.76; 95% CI, 0.55-1.05) and a positive association among Caucasians (OR, 1.40; 95% CI, 0.95-2.04).

CONCLUSIONS

This review suggests that genetic polymorphisms in tumour invasion could be candidate biomarkers of GC risk. However, differences between populations and stages of cancer need to be taken into account and may explain some of the inconsistencies found in previous studies.

Interleukin-10 -1082 promoter polymorphism associated with gastric cancer among Asians

Studies investigating the association between interleukin-10 (IL-10) -1082 promoter polymorphism and gastric cancer risk report conflicting results. The objective of this study was to quantitatively summarise the evidence for such a relationship. Two investigators independently searched the Medline and Embase databases. This meta-analysis included 13 case-control studies, which included 2227 gastric cancer cases and 3538 controls. The combined results based on all studies showed that there was no significant difference in genotype distribution [AA odds ratio (OR)=0.92, 95% confidence interval (CI)=0.73, 1.14; AG (OR=1.09, 95% CI=0.87, 1.36); GG (OR=1.03, 95% CI=0.85, 1.25)] between gastric cancer and noncancer patients. When stratifying for race, results were similar except that patients with gastric cancer had a significantly lower frequency of AA (OR=0.71, 95% CI=0.52, 0.97) and higher frequency AG (OR=1.53, 95% CI=1.15, 2.03) than noncancer patients among Asians. When stratifying by the location of gastric cancer, we found that patients with cardia gastric cancer had a significantly lower frequency of AA (OR=0.53, 95% CI=0.34, 0.83) and higher frequency AG (OR=1.50, 95% CI=1.06, 2.11) than those with noncardia gastric cancer among Caucasians. When stratifying by the Lauren's classification of gastric cancer, we observed no statistically significant differences in genotype distribution. This meta-analysis suggests that the IL-10 -1082 promoter polymorphism may be associated with gastric cancer among Asians, and that differences in genotype distribution may be associated with the location of gastric cancer.